evinrude 9.9 1979 poor idle,loud exhaust,less power

[Rick.]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

Well glad to hear no salt and a fellow Canadian to boot. Fresh water will wreck it also but it might take a bit longer. Hugh I own a 79 - 9.9 and you don't need to pull the power head to get the cylinder head off. As I recall I had to remove the cowl latch and some plug wire holders and that was about it. Do keep us posted and I hope you get all the wind your looking for. Rick.

 

[Hughjohnson]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

Now I feel better .I'll go and take another look at it this morning. I am using a Seloc Vol II Johnson/Evinrude Outboard Repair Manual. Do you use one that might be better. Hugh

 

[Rick.]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

Try to get an original paper OMC service manual for your model. I normally get them on Ebay. Johnson or Evinrude will be the same. Service manuals are a great help but sometimes they assume we have base knowledge. They say 'disconnect the shift rod' for instance but an hour later I still haven't found the connection. All in all OMC is the only way to go IMO. Rick.

 

[Hughjohnson]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

Well today I bought a compression tester and the results 110 and 120 psi. The pressure built up in about 3 to 4 cycles on each cyl .Big surprise I expected more difference. I do not know if the throttle was wide open because I had to be in neutral for the electric starter to work.Re the manuals Is OMC and Johnson/Evinrude the same company? Hugh

 

[nwcove]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

great comp numbers, id now rule out head gaskets issues. now get a proper spark test tool, or make your own from a new plug.

 

[OptsyEagle]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

That compression is not bad. It is just within 10% of each other so I would like to think that it would not create a noticeable problem. You can still have water leaking into a cylinder and still get good compression, so we can't rule out a head gasket just yet, but your results are encouraging. You don't need the throttle wide open on a 2 stroke for compression testing.

You should do a proper spark test to get a look at why you are losing a cylinder. If you are getting a good gap jump (greater then 7/16") then perhaps water is getting in the cylinder. If not, the problem is probably ignition related.

Another test you can do, is to switch the coils. You know which cylinder is failing, so switch the spark boots to the other cylinders and the clips to the opposite clip. Run it again and verify if the same cylinder is failing or if the problem switches to the other cylinder. This info will tell you the following:

If the problem switches to the other cylinder: it is not a water in cylinder problem and is maybe a coil problem but may also be a powerpack problem (I am not too familiar with the CDI powerpacts on your motor to advise).

If it doesn't switch to the other cylinder it may be a water in cylinder problem or may be a powerpack problem.

Anyways, it would be useful to know and a fairly easy test.

Yes, The Outboard Marine Company (OMC) was the manufacturer of the Evinrude and Johnson brands. Those brands are now owned by Bombardier Recreational Products (BRP).

 

[Rick.]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

Well darn it anyway. I thought we were getting close to the end. I'm content with your compression numbers. Could be better but hey it's a 79 not a 2009. Have you at any time noticed water on either of the plugs? Have you ever noticed white exhaust coming out of the relief ports at the top of the stern of the leg? If you have I would take a wrench and snug up all the bolts on the exhaust cover. I haven't got my manual at home but perhaps someone will give the torque numbers for them. If not I'll look tomorrow at my office. I had issues with my 79 getting water into the bottom cylinder. To pull the exhaust cover I couldn't get the lower bolt/bolts (can't remember) out without pulling the power head so I just tightened them all up and it worked for me. Some time ago someone posted you could get the exhaust cover off without pulling the power head but I didn't figure out how. Just to rub it in a bit Hugh, are you starting to see a common denominator in so many of these posts? (spark gap check. LOL) Rick.

 

[AlTn]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

Looking at the OMC manual for a 1978 9.9...no torque value for the exhaust cover..head screws...216-240 INCH pounds....

 

[Hughjohnson]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

yes a mystery. How do you make a spark test tool from a new plug. I have tried a new plug and the spark looked good and consistent but not under 150 psi pressure. I suppose I could try the new plug on the good cylinder wire and see if that spark is any fatter and that would tell me there is a difference.
next question;does anyone know if you are not firing on a cylinder whether that cylinder will clean up the way it does when water gets into it. Because the bad cylinder is very clean. Hugh

 

[OptsyEagle]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

yes a mystery. How do you make a spark test tool from a new plug. I have tried a new plug and the spark looked good and consistent but not under 150 psi pressure. I suppose I could try the new plug on the good cylinder wire and see if that spark is any fatter and that would tell me there is a difference.
next question;does anyone know if you are not firing on a cylinder whether that cylinder will clean up the way it does when water gets into it. Because the bad cylinder is very clean. Hugh

This spark tester design is from Leeroy's site. It works good. Easy to build. The top part is metal with the grounding clip attached. The middle part is wood and the bolts are where the spark plug boots go. The distance from the end of the bolt to the top part is your gap. I put black electrical tape on the back so that the spark is easier to see.

I don't like sending you out to do more tests, but you will find that "swapping the coils" test I mentioned in my last post could provide very useful information.

Water in a cylinder will usually clean it up but even a well working cylinder can end up being fairly clean.

 

[Rick.]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

Water intrusion will clean a cylinder. Enough water will kill even the strongest spark. Water intrusion tends to produce white smoke (vapor) at the exhaust. You you ever noticed any? I'm keeping my fingers crossed that once you tighten up the exhaust cover bolts your engine will be back to normal. Rick.

 

[Hughjohnson]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

I thought you had all gone away but then I discovered there was a 2nd page. As I said before i am new to these forums but wow is it good .I cannot believe the help you are all giving me. This is what life should be like; helping each other.

well yes i will do more ignition tests as suggested and look for white exhaust. I notice that when in reverse exhaust comes out of the relief ports so I will do that too to see if it white and tighten the exhaust cover. Thanks to you all Hugh

 

[Hughjohnson]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

No there is no visible white exhaust. All other tests will have to wait a few days till I get back from vacation . Hugh

 

[Hughjohnson]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

Well I'm back . went to the boat and tested the spark on each of the 2 cylinders. The result is that both are the same at 12mm or nearly half and inch. I adjusted the gap between a rigid piece of wire and the ground until there was no spark and both cylinders stopped at about 12 mm.So I do not have an ignition problem and I;m glad I have that out of the way. I also confirmed that the bad (clean) cylinder does fire occasionally because when I was testing the good cylinder for spark the bad cyl occasionally fired.
I checked the bolts on the exhaust manifolds as best as I could and they seem fine with no visible exhaust marks where I could see.
What I cannot understand is if the compression is OK how can the cyl head gasket be leaking so much water that the cyl will not fire.Anyone had this experience where just a small leak can stop the cyl firing ? Hugh

 

[nwcove]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

have you tried a compression test after the motor was warmed up? i had (still have) an 85 rude that ran great , for awhile, until it got up to operating temp, then it would blow water and steam from the tell tale. it had a bad head gasket, but was leaking exhaust into the water jacket, not water into the cylinder. but this can go the other way.....water into the cyl and not the jacket. my probs only showed up after the engine got up to operating temps. ?

 

[Hughjohnson]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

Interesting i will check compression when hot but my engine behaves the same hot as cold so not likely the same problem

 

[OptsyEagle]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

Well I suppose it is time to take the cylinder head off and pay close attention to the head gasket for a leak between the water side and the cylinder in question.

The other thing it could be is a fuel pump leak into the bad cylinder. If the fuel pump receives its pulses from the good cylinder, then this is not the problem, but if it is the bad cylinder you can check it by removing the fuel pump from the motor (two screws) and pumping the primer bulb to see if gas leaks out. It shouldn't, but if it does it could be flooding the bad cylinder.

My last thoughts are the crankcase seals. The one sealing the bad cylinder would be the one I would go look at (after I did the other two checks), either the upper or lower crankcase seal.

Now my last comment is; even if the seals are bad the question you need to ask is how bad are they? It is possible that the bad cylinder is firing but perhaps is not putting out the previous power as it did before due to a slight loss of seal, but would still be burning any gas that gets into the combustion chamber (because it is firing). This thread got started with you saying that your boat speed dropped from 6.4 knots to 5.2 knots. I am pretty sure my boat drops like that if my fat neighbor decides to go fishing with me, so I am not sure that in inself signifies a big problem with your motor. You know your motor better then me so I will leave that thought with you.

 

[the machinist]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

You may have a bad electrical connection. This could be at the boot for the spark plug, or in the rubber boot connector near the head that leads to the coils. Or a bad ground under that coil.

I think Bob may have mistakenly thought your motor was a 9.5hp in relationship to a exhaust hose leak.

In your intial post you mention a loud barking noise. This motor could have a bad upper motor mount grommet which is right under the lower pan couling at the top of the exhaust housing. If this mount is bad the motor has upper forward/rearward slop & the rubber grommets will also be bad. This allows some exhaust to be blown out there which is usually evident by black oily residue. The grommet could be bad without the mounts going, but that is rare.

 

[Hughjohnson]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

Thanks guys I'll do some further checking when I get a chance. I cannot take the cyl head off just yet cos I need the engine too often and do not have a spare. Hugh

 

[Hughjohnson]

Re: evinrude 9.9 1979 poor idle,loud exhaust,less power

Hi guys I am back after 3 months. the engine is on its stand in the garage and I am going to check the cylinder head gasket. The suspicion is that water is getting into the failed cylinder. to get the lower 2 cylinder head bolts out i have to lift the engine a few inches to clear the lower cowling (motor cover ). My manual does not describe this well (not at all ) and I have not been able to find an OMC manual yet on ebay.
Please let me know if I have to do the following. Remove 6 screws between the exhaust housing assembly and the bottom of the engine block. And that when I remove the engine the lower cowling will come with it .And I will be pulling the square inner exhaust housing and water tube with the engine. Also is there a chance that the drive shaft will also come up away from the water pump assembly or is the shaft attached at the bottom. I assume that I will then have to remove the lower cowling from the engine with the 3 engine mounting bolts.
Hope you can help. My model no. is 108350 and it is in fact a 1978 and not a 1979 as the thread is titled. Hugh